[tools/perf] Reference legacy_page_test module instead of page_test

tools/perf/measurements/smoothness.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-from telemetry.page import page_test
+from telemetry.page import legacy_page_test
 from telemetry.timeline import tracing_category_filter
 from telemetry.web_perf import timeline_based_measurement
 from telemetry.web_perf.metrics import smoothness
 
 
 class _CustomResultsWrapper(timeline_based_measurement.ResultsWrapperInterface):
 
   def __init__(self):
     super(_CustomResultsWrapper, self).__init__()
     self._pages_to_tir_labels = {}
 
   def _AssertNewValueHasSameInteractionLabel(self, new_value):
     tir_label = self._pages_to_tir_labels.get(new_value.page)
     if tir_label:
       assert tir_label == self._tir_label, (
           'Smoothness measurement do not support multiple interaction record '
           'labels per page yet. See crbug.com/453109 for more information.')
     else:
       self._pages_to_tir_labels[new_value.page] = self._tir_label
 
   def AddValue(self, value):
     self._AssertNewValueHasSameInteractionLabel(value)
     self._results.AddValue(value)
 
 
-class Smoothness(page_test.PageTest):
+class Smoothness(legacy_page_test.LegacyPageTest):
 
   def __init__(self, needs_browser_restart_after_each_page=False):
     super(Smoothness, self).__init__(needs_browser_restart_after_each_page)
     self._results_wrapper = _CustomResultsWrapper()
     self._tbm = None
 
   @classmethod
   def CustomizeBrowserOptions(cls, options):
     options.AppendExtraBrowserArgs('--enable-gpu-benchmarking')
     options.AppendExtraBrowserArgs('--touch-events=enabled')
@@ skipping 32 matching lines @@
         '--enable-threaded-compositing',
         '--enable-gpu-benchmarking'
     ])
 
 
 class SmoothnessWithRestart(Smoothness):
 
   def __init__(self):
     super(SmoothnessWithRestart, self).__init__(
         needs_browser_restart_after_each_page=True)